Spyke
Knusper
feddit.de

In this thread: Trying to guess the programming language based on a single keyword and angle brackets. ๐Ÿ™ƒ

43
UFO
programming.dev

In Scala:

case class Fix[F[_]](unfix: F[Fix[F]])
case class Pie[T](filling: T)
def ohNo: Fix[Pie] = Fix(Pie(ohNo))
16
lemmy.world

Which language are we talking here? Cpp? Because typeof hasn't ever seemed useful to me in how I use cpp or how I have ever really used a language. I also remember it being criticized in java class more than 20 years ago when OOP was solely preached, even for scientific people like me.

-22
mozingoreply
lemmy.world

This sure looks like C#. I use typeof every once in a while when I want to check that the type of a reference is a specific type and not a parent or derived type. But yea, really not that often.

36
morhpreply

Java only has instanceof and getClass, not typeof.

16
SGHreply

Standard C does not have typeof. That's just a compiler extension...

Also the equivalent of typeof is most likely decltype or auto.

3

Typescript! Though it's less useful, since the Typescript types aren't available at runtime, so you'll just get object for non-primitive values.

2

Probably because Java and C# take much inspiration from C++. They aren't called "C-based" languages for nothing ๐Ÿ˜‰

1
r00tyreply

Yeah in C# it has quite a few uses.

I'm working on a background fun project where there's a base class that is for olde style CPU emulation. Where you can derive a class from the base class and essentially design 8bit style CPUs.

I have a separate class as a generic Assembler that will work with any of the created CPUs. But, to be able to do that I need to be able to get information about instructions, arguments, opcodes, registers etc from the derived class.

So the assembler is instantiated with Assembler\ and then it uses typeof to instantiate the actual CPU class being used to get all the information.

So, that's just an example of when you'd use something like this.

3
tonurreply
feddit.dk

I have used typeof(T) inside the generic class, so fx a function inside the class Pie where T can be refered. But out of context, if you were to call typeof(T) inside Program.cs's main function, it would not work.

5
Kogasareply
programming.dev

I don't get what you mean. You can define class Pie and instantiate it with the type argument Pie.

Huh, maybe I don't get it because Lemmy is literally erasing angle brackets from our messages. Not just "not rendering." It's removing them entirely. There should be four angle brackets in the first line of this comment...

1
mordack550reply
lemmy.world

Your assumption that "using reflection means the code is wrong" seems a bit extreme, at least in .Net. Every time you interact with types, you use reflection. Xml and Json serialization/deserialization uses reflection, and also Entity Framework. If you use mocking in test you are using reflection.

We have an excel export functionality on our sites that uses reflection because we can write 1 function and export any types we want, thanks to reflection.

16

huh, youโ€™re right! Iโ€™m trained on a different kind of code. In C# in particular, which I use mostly to do sneaky stuff (patch/inject runtime code to, um, โ€œfixโ€ it) and when I see a project that itโ€™s too clean it smells

I also see python code (I code regular stuff in it) that could be written much more cleanly using monkey-patching

1

Modern .NET is reducing dependence on reflection. System.Text.JSON and other core libraries have leveraged source generation to produce AOT + trim friendly, reflection free code. But yeah, it's not a taboo like say dynamic, it's perfectly normal to use reflection in idiomatic C# code.

2
_Z1userireply
sopuli.xyz

Hm, I'm currently working on a project with a ton of runtime-configurable plug-ins and dependencies between them. All of that is held together with a copious amount of black QMetaObject magic. I had the same thought about it, but I'm not sure how you'd get similar functionality without reflection and not making it even more convoluted and fragile...

5
xmunkreply
sh.itjust.works

Metaprogramming is extremely useful for long term code readability. What you're doing is probably fine but we can't really evaluate that without seeing the actual code.

3

That's why I stopped writing code and started writing ASTs and AST transformers that can be configured to emit libraries.

2

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